Medical fluid injectors are motorized devices that expel fluid, such as contrast media, from a syringe, through tubing, and into a subject such as a person or animal. Medical fluid injectors are generally adjustably fixed to a stand or support and have a drive ram that interfaces with a plunger of the syringe. This drive ram may be used to drive the plunger forward to expel fluid from the syringe and to pull the plunger rearward to draw fluid into the syringe.
Conventional injectors have included a variety of designs for engagement mechanisms that provide at least a temporary interface between the drive ram of the injector and the plunger of an associated syringe. However, there have been difficulties with such engagement mechanisms. For instance, some may say the engagement mechanism of one conventional injector may cause uneven loading of the plunger, which may contribute to leakage of fluid being drawn into and/or expelled out of the syringe. As another example, some may say the engagement mechanism of another conventional injector may tend to fail under the tensile load of a normal injection procedure, thus resulting in the drive ram slipping off of the plunger.